EA I-U-T Girder System

ABSTRACT

A precast concrete beam including a substantially planar web extending longitudinally between ends of the beam; a pair of flanges formed integrally with the web, each flange extending laterally from an elongate edge of the web and extending longitudinally between the ends of the beam so as to define a structure engaging surface of the beam; and a plurality of diaphragms formed integrally with the web and the flanges, each diaphragm spanning laterally between a side of the web and one of the flanges, wherein the diaphragms are spaced apart along the beam to thereby support the flanges.

RELATED APPLICATIONS

There are no previously filed, nor currently any co-pendingapplications, anywhere in the world.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to precast concrete beams and,more particularly, to such precast concrete beams particularly adaptedfor long span use in the construction of bridges or the like. Further,also to our proprietary Untra-High-Performance-Concrete Mix (UHPC Mix)trademarked as EASSCM-UPHP, this is used in combination with ourdesigns.

2. Description of the Related Art

Precast concrete beams are currently used in the construction of bridgesand other related structures. A range of different beam type is commonlycharacterized by their cross section shape, i.e., T-beams, I-beams or U(Tub Beams). Each has benefits depending on the particular structuralapplication.

Having a characteristic “T”-shaped cross section, T-beams are oftenutilized in bridge construction to providing a vertical web topped withhorizontal flanges supporting a road surface deck and distributing loadsfrom the edges of the beam to the vertical web. Prestressedreinforcement members may be provided, particularly at its base, withinthe T-beam. To allow for fewer beams and/or long spans, strengthimprovements over conventional T-beam designs are provided by using a“U”-shaped central portion in lieu of a vertical web, with the bottom ofthe “U” forming a base of the beam and with horizontal flanges extendlaterally. Greater beam widths result from supporting the flangescantilevered from the beam centerline, with a thicker base providingimproved bending strength.

Although such improvements allow for longer bridge spans and/or areduced number of beams to provide a bridge of a particular width, suchbeams are heavier, complicating installation, and have a more complexgeometry that complicates inspection, validation, maintenance, etc.

Consequently, a need exists for an improved beam design adapted for longspan use in the construction of bridges or the like without one or moreof these complexities.

SUMMARY OF THE INVENTION

It is thus an object of the present invention to provide a precastconcrete beam particularly adapted for long span use in the constructionof bridges or the like.

It is a feature of the present invention to provide a beam an enlargedbulb formed integrally with the web and opposite upper flanges.

Briefly described according to the present invention, a beam design isprovided for use in construction of a long span bridge structure. Thebeam includes a generally vertical web extending longitudinally betweenan upper horizontal planar support formed and a lower enlarged bulb. Theupper horizontal planar support extends cantilevered outward from eachside of the web to form a pair of opposing flanges. The enlarged bulb isalso formed integrally with the web. The enlarged bulb is shaped havinga horizontal lower edge, a pair of vertical opposed side edges, andtapering angularly upward from the side edges to the web. A plurality ofdiaphragms is formed integrally with the web and spaced apart along thebeam and supporting the flanges. Each diaphragm extends from the side ofthe web and between one of the flanges and the angularly upward taper ofthe bulb. The diaphragms may be formed in pairs that span betweenrespective sides of the web and respective flanges at the samelongitudinal position along the beam. Further, the pairs of diaphragmsmay be spaced apart by a spacing distance selected so that a loadapplied to outer portions of the flanges will be transmitted to the webvia the diaphragms. A plurality of reinforcing members may extendlongitudinally through the bulb, the web, and/or the flanges.

According to one aspect of the present invention, an improved I-beamconfiguration is provided to allow for a bridge span design exceeding250 feet. Such a beam configuration is structurally sound, moreexpeditious to build and significantly cheaper than current traditionalsystems, with projected cost savings exceeding about 46% over otherwiseconventional span bridge designs.

According to another aspect of the present invention, the improvedI-beam configuration may be further provided to allow for a bridge spandesign reaching 350 feet. Such a beam configuration is structurallysound, more expeditious to build and significantly cheaper than currenttraditional systems, with projected cost savings exceeding about 81%over otherwise conventional steel-plate girder bridge designs.

According to yet another aspect of the present invention, the improvedU-beam configuration may be further provided to allow for a bridge spandesign reaching 350 feet. Such a beam configuration is structurallysound, more expeditious to build and significantly cheaper than currenttraditional systems, with projected cost savings exceeding about 79%over otherwise conventional truss or arch bridge designs.

It is anticipated that the beam would be cast from concrete as a unitarybody, with the reinforcing members being prestressed prior to casting.

An advantage of the present invention is that is allows for longerbridge spans and/or a reduced number of beams to support a particularstructure.

Another advantage of the present invention is that it provides a beamthat is lighter for a particular span length than other availableconfigurations.

Yet another advantage of the present invention is to provide a beamdesign that allows for a less complicated installation.

It is other advantages of the present invention to provide a beamgeometry facilitates inspection, validation, maintenance and the like.

Further objects, features, elements and advantages of the invention willbecome apparent in the course of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will become betterunderstood with reference to the following more detailed description andclaims taken in conjunction with the accompanying drawings, in whichlike elements are identified with like symbols, and in which:

FIG. 1 is a schematic perspective view of a portion of a precastconcrete beam according to a preferred embodiment of the presentinvention;

FIG. 2 is a schematic end view thereof;

FIG. 3 is a schematic top view thereof;

FIG. 4 is a schematic side view of the end portion thereof;

FIG. 5 is a schematic cross section view thereof taken along sectionVA/of FIG. 4;

FIG. 6 is a schematic cross section view thereof taken along sectionVI-VI of FIG. 4;

FIG. 7 is a schematic cross section view thereof taken along sectionVII-VII of FIG. 4;

FIG. 8 is a schematic cross section view of an example of a bridgestructure formed using the precast concrete beams according to apreferred embodiment of the present invention;

FIG. 9 is a schematic cross sectional view of a beam bridgeconfiguration according to an alternate embodiment of the presentinvention;

FIG. 10 is a cross sectional view taken along line X-X of FIG. 9 showingthe individual precast U-beam configuration;

FIG. 11 is an exemplary truss panel for use therewith;

FIG. 12 is a cross sectional view of a composite deck panel taken alongline XII-XII of FIG. 11;

FIG. 13 is a cross sectional view of the U-beam design of FIG. 9 shownwith steel reinforcement tubes incorporated therein;

FIG. 14 is an exemplary elevational view of a truss system incorporatingthe U-beam designs of FIG. 13;

FIG. 15 is an exemplary cross sectional view of a decked I-beam (“DIB”)bridge design shown according to the present invention for a design of a350 foot span;

FIG. 16 is a schematic cross section view taken along line XVI-XVI ofthe DIB bridge deck section of FIG. 15;

FIG. 17 is a cross section of the transfer ribs of the design of FIG.16;

FIG. 18 is an exemplary configuration of a midspan of the DIB designshowing the truss design and configuration;

FIG. 19 is a bursting reinforcement detail of the DIB design; and

FIG. 20 is an exemplary cross sectional view of a decked I-beam (“DIB”)bridge design shown according to the present invention for a design of a250 foot span.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The best mode for carrying out the invention is presented in terms ofits preferred embodiment, herein depicted within the Figures. It shouldbe understood that the legal scope of the description is defined by thewords of the claims set forth at the end of this patent and that thedetailed description is to be construed as exemplary only and does notdescribe every possible embodiment since describing every possibleembodiment would be impractical, if not impossible. It should also beunderstood that, unless a term is expressly defined in this patent thereis no intent to limit the meaning of that term, either expressly or byimplication, beyond its plain or ordinary meaning, and such term shouldnot be interpreted to be limited in scope based on any statement made inany section of this patent (other than the language of the claims). Tothe extent that any term recited in the claims at the end of this patentis referred to in this patent in a manner consistent with a singlemeaning, that is done for sake of clarity only so as to not confuse thereader, and it is not intended that such claim term by limited, byimplication or otherwise, to that single meaning. Finally, unless aclaim element is defined by reciting the word “means” and a functionwithout the recital of any structure, it is not intended that the scopeof any claim element be interpreted based on the application of 35U.S.C. § 112(f).

The best mode for carrying out the invention is presented in terms ofits preferred embodiment, herein depicted within the Figures.

1. Detailed Description of the Figures

Referring now to the drawings, wherein like reference numerals indicatethe same parts throughout the several views, a precast concrete beam,generally noted as 10, is shown according to a preferred embodiment ofthe present invention for use in long span bridge structures 100 or thelike. The beam 10 may include a generally vertical and planar web 12extending longitudinally between its upper edge 14 and its lower edge16. A generally horizontal planar support 18 is formed at the upper edge14 formed integrally with the web. The planar support 18 extendslongitudinally outward from the centerline A-A of the web 12 to form apair of flanges 18 a, 18 b. The flanges 18 a, 18 may extend along theentire length of the beam 10. In some embodiments each flange 18 a, 18 bmay be substantially perpendicularly to the centerline A-A. In otherembodiments, the flanges 18 a, 18 b may be formed extending laterally atan angle relative to the centerline A-A.

The lower edge 16 may form an enlarged bulb 20 integrally as anextension of the web 12. The bulb 20 may be reinforced and otherwiseadapted for improving torsional rigidity and bending strength along theentire cross section of the beam 10. In a preferred embodiment the bulb20 may form a generally boxlike structure at the lower edge 16 having abase 22, a pair of vertical opposed side edges 24, and taperingangularly upward 26 from the side edges 24. As envisioned, the beam maybe cast as a prestress unitary concrete body. It is further envisionedthat such casting may be performed remote from the final installationand, as such, the base 22 may provide a support surface for the beam 10when transported between locations.

The beam 10 further includes a plurality of diaphragms 30. Eachdiaphragm 30 may be formed integrally with the web 12 and spaced apartalong the beam 10. The diaphragms 30 support the flanges 18 a, 18 b.Each diaphragm 30 may span laterally between a side of the web 12 andone of the flanges 18 a or 18 b, respectively.

Referring best in conjunction with FIG. 7, each diaphragm 30 may spanangularly between a flange 18 a/18 b and an upward taper 26 of the bulb20. A plurality of such diaphragms 30 may spaced apart along the beam10. Preferably diaphragms 30 are formed as pairs between respectivesides of the web 12 and respective flanges 18 a, 18 b. More preferablythe pairs of diaphragms 30 are positioned at the same longitudinalposition along the beam and spaced at a distance sufficient such that aload applied to an outer portion of one of the flanges will betransmitted to the web via one of the diaphragms. It is even morepreferable that the spacing 32 of the diaphragms 30 is less than 30times a flange thickness 34 of the flanges 18 a, 18 b.

As shown in conjunction with FIG. 7, each diaphragm 30 spans between aside of the web 14 and one of the flanges 18 a, 18 b and the angularlyupward taper 36 of the bulb 20.

As shown best in conjunction with FIG. 5, the beam 10 may furthercomprise one or more end blocks 40. Each end block 40 may be formed atthe outermost ends of the beam 10. Each end block 40 may be formed as avertical extension between opposed side edges between the bulb 20 to theflanges 18 a, 18 b. It is preferred that each end block 40 may be castfrom concrete as part of the unitary body.

A plurality of reinforcing members 42 may be provided extendinglongitudinally about the beam 10. The reinforcing members 42 may beprovided throughout the various structures of the beam 10, includingwithin the bulb 20, the web 14 or the horizontal planar support 18.

The configuration of the beam 10 as described may allow for the use ofwider beams. The use of wider beams provide improved structural rigidityfor use in long spans. This may be provided with the use of wider beamsto provide improved performance that may allow for a reduction in thenumber of beams required for a given span.

In a preferred embodiment the beam 10 may be cast from concrete as aunitary body. Accordingly, the web 18, diaphragms 30, and flanges 18 a,18 b may be integrally formed together. Further, the reinforcing members42 may be prestressed prior to the casting of the beams 10.

Referring now to FIG. 3-4, the diaphragms 18 a, 18 b may be spaced apartby a spacing “L”. The spacing “L” may be of a distance sufficient suchthat a load applied to an outer portion of one of the flanges 18 a, 18 bwill be transmitted to the web 14 via one of the diaphragms 30. In apreferred embodiment the spacing distance “L” may be less than 30 timesa flange thickness “T” of the flanges 18 a, 18 b.

Within the prestressed cast concrete structure, internal reinforcements42 may be incorporated. Such reinforcements 42 may be included along thebeam 10 at locations that correspond with locations of the diaphragms30. Reinforcement members 42 may be provided in the form of bars, rods,cables or strands, generally made from a material having a relativelyhigh tensile strength compared to the concrete used to make the precastconcrete beam 10. Preferably such material may be steel. Morepreferably, such material may be formed of carbon fiber composite cable(“CFCC”). Whatever the material, one or more of the reinforcementmembers 42 may be prestressed when the beam 10 is formed. This may beachieved by positioning the reinforcement members 42 within the castingprocess and creating a tensile loading before the beam 10 is cast inconcrete. This will cause portions of the beam 10 to be in a compressedupon curing, which allows for increased tensile load bearing capacity.

Finally, as best shown in conjunction with FIG. 1 and FIG. 5, each beam10 may terminate at one or both ends with an end block 40. It ispreferred that each end block 40 may be integrally formed with the web20, but having an increased thickness compared to the thickness of theweb “T”. It is more preferable prestressed reinforcement members 42 maytraverse through the end blocks 40.

2. Operation of the Preferred Embodiment

As shown best in conjunction with FIG. 8, in operation the beams 10allow for use in large span surfaces 100, greater than would otherwisebe attainable. The large services span may further be achieved withadditional support. The overall strength added by the diaphragms 30 alsoprovide additional support for the horizontal planar support 18.

Further, it is anticipated that the beams 10 may be precast off-sitefrom a final installation. As such they may be preformed as aprestressed structure.

It should be apparent to those having ordinary skill in the relevantart, in light of to present teachings, that a number of modificationsand variations may exist to the configuration(s) described. It shouldalso be understood that utilizing an effective long span, wide flanged,prestressed girder may be provided for the construction of long spanapplications such as bridges or the like. By providing such beams 10,bridges or similar structure may be constructed using precast concretebeams in accordance with the present invention that allows for longerbridge spans and/or a reduced number of beams to support a particularstructure. Each beam is lighter for a particular span length than otheravailable configurations, and with a design that allows for a lesscomplicated installation. Further, the beam geometry facilitatesinspection, validation, maintenance and the like.

As shown in conjunction with FIG. 9 through FIG. 14, an improved precastconcrete beam is shown according to an alternate embodiment of thepresent invention showing a U-beam configuration. Preliminary analysisshows that section configuration as shown is adequate to resist thebending moment demand using approximately (150) 0.7-in, strands in eachmember. A close-up of the cross-section of the beam is shown in FIG. 10.It was estimated that no. 4 grade 60 hooked bars may be placed in eachtop bulb at 12-inch spacing to resist the interface shear demand. Such aspacing fits inside the voids of the precast truss panel, allowing forcomposite connection between the beams and the top slab. Such a deckslab may consists of a 1.5-inch thick precast UHPC layer with two weldedwire steel trusses and a 6.5-in. thick CIP conventional concrete (CC)layer that placed at time of construction as shown in FIG. 11.

The cross-section of the composite deck panel is shown in FIG. 12. Tofurther optimize the shape, a middle third of the beam has webs replacedwith hollow structural sections (“HSS”) steel tubes to reduce the weightof the precast beam. The cross-section of the tub beam, including thesesteel tubes, are shown in FIG. 13. The steel tubes are placed as a trusssystem along the length of the beams, an elevation view is shown in FIG.14. These beams are also subjected to very high prestressing forces atrelease. To prevent cracking of the member at time of release, steelwill need to be added within a distance of h/4. However, thecontribution due to the fibers can be accounted for. For the tub beams,approximately twelve no. 7 grade 60 bars are needed at each end, withsix bars being in one web and six bars being in the other. The fibersare assumed to be able to carry the rest of the stress. Such aconfiguration may allow for larger girder systems to be used for abridge deck, while requiring a fewer number of girders overall. Whilethe larger girders themselves may be larger, heavier and potentiallymore expensive than conventional girders, the use and installation of afewer number of girders allows for overall savings in weight, cost andinstallation time.

Referring to FIG. 16 through FIG. 19, a Decked I-Beam System Designutilizing the present teachings is shown in an exemplary span of 350feet. Similar to the “U” tub beam, the 350 foot span decked I-beam (DIB)bridge system uses four DIBs that are 12 feet in depth with a beamspacing of 12-ft 8-in. Rather than using a deck slab or the showncomposite truss panel, the deck is integrated into the beam, allowingfor simple and quick production. The deck is ribbed to save on materialcosts, as the entire depth is not needed to obtain sufficient strengthand resist transverse bending. Bars can be placed transversely in theseribs to provide enough bending strength as well as for a jointconnection. The cross-section of the bridge is shown in FIG. 15. Notethat the transverse bars are not shown in this section for clarity.

Preliminary analysis shows that the provided section is adequate toresist the bending moment demand using approximately (90) 0.7-in,strands in each member. (24) holes, approximately 6/8-in, in diameterare also provided in the top flange to allow for future post-tensioningof 0.5-in, strands. This allows for camber to be adjusted on site.

A close-up of the cross-section of the beam is shown in FIG. 16. Notethe big gap between strands in the center of the beam. This allows forthe UHPC mix to be able to flow uninterrupted to the bottom, helpingprevent any fiber bridging between center strands. Tentatively, no. 6grade 60 bars are placed in the top and bottom of each rib to allow forsufficient connection of the beams, as well as to resist any positiveand negative bending of the integrated deck.

The cross-section of the ribs is shown in FIG. 17. To further optimizethe shape, the beam would be formed as a truss beam for the middle 60percent of the length. This is shown in FIG. 18. Triangular shaped voidswould be formed using expanded polystyrene (EPS) or similar. Thissubstantially reduces both the weight of the member and the amount ofmaterial needed. Previous research and testing of UHPC members did notshow any issues with including these large opening, so it is assumedthat this detail would not create issues with stress and strengthdemands. These beams are subjected to very high prestressing forces atrelease. To prevent cracking of the member at time of release, steelwill need to be added within a distance of h/4. However, thecontribution due to the fibers can be accounted for. For the decked!-beam, approximately (6) no. 6 grade 60 bars are needed at each end.The fibers are assumed to be able to carry the rest of the stress.

Placement of the bursting reinforcement is shown in FIG. 19. It shouldbe noted that according to existing codes and design guides of thePrecast/Prestressed Concrete Institute, the longest pre-stressed precastI-beam known is around 220 ft. Utilizing the teachings of the presentinvention, possibilities now exist for Long Span Bridges utilizing UHPCor similar concrete mix designs in excess of 220 feet. For the 250′ spanI-beam, a member has similar framing to that of the 350 ft span design,but the beams are 9 ft deep and approximately 9 ft wide. Thecross-section of this beam is shown in FIG. 22. The design of this beamshows that (54) 0.7-in, strands are adequate for this span.Additionally, (26) holes are placed in the top of the member to allowfor in-field post-tensioning of 0.5-in. strands so that the camber canbe adjusted as needed.

Note that the main difference in the 350 foot span beam and the 250 footspan beam is the joint shape. The joint shape in the 350 ft span shows ajoint that is easy to form for field casting where backer rod can beplaced in the bottom flanges, while this beam uses a more standarddetail. This beam also uses the same ribbed section as shown previouslyand shown here in FIG. 22 For this section, it is assumed that a no. 6grade 60 bar will need to be placed in the bottom of each rib, similarto the other DIB (350′) CIP Design, but without the top bar. This meansthat the fibers are relied on to resist the negative bending moment. (6)no. 6 bars would also need to be placed in each end to resist burstingstresses.

The foregoing descriptions of specific embodiments of the presentinvention are presented for purposes of illustration and description.The Title, Background, Summary, Brief Description of the Drawings andAbstract of the disclosure are hereby incorporated into the disclosureand are provided as illustrative examples of the disclosure, not asrestrictive descriptions. It is submitted with the understanding thatthey will not be used to limit the scope or meaning of the claims. Inaddition, in the Detailed Description, it can be seen that thedescription provides illustrative examples and the various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed subject matter requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed configuration or operation. The followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but is to be accorded the full scope consistent with thelanguage claims and to encompass all legal equivalents. Notwithstanding,none of the claims are intended to embrace subject matter that fails tosatisfy the requirement of 35 U.S.C. § 101, 102, or 103, nor should theybe interpreted in such a way. Any unintended embracement of such subjectmatter is hereby disclaimed. They are not intended to be exhaustive norto limit the invention to precise forms disclosed and, obviously, manymodifications and variations are possible in light of the aboveteaching. The embodiments are chosen and described in order to bestexplain principles of the invention and its practical application, tothereby enable others skilled in the art to best utilize the inventionand its various embodiments with various modifications as are suited tothe particular use contemplated. It is intended that a scope of theinvention be defined broadly by the Drawings and Specification appendedhereto and to their equivalents.

1. A beam for use in construction of a long span bridge structurecomprising: a generally vertical web extending longitudinally between afirst terminus and a second terminus; a generally horizontal planarsupport formed integrally with the web at an upper terminus andextending cantilever to form a pair of opposing flanges; an enlargedbulb formed integrally with the web at a lower terminus and opposing theupper terminus, said bulb further having a horizontal lower edge, a pairof vertical opposed side edges, and tapering angularly upward from theside edges to the web; a plurality of diaphragms formed integrally withthe web and spaced apart along the beam supporting the flanges, eachdiaphragm spanning laterally between a side of the web and one of theflanges and the angularly upward taper of the bulb; and a plurality ofreinforcing members extending longitudinally between the first terminusand the second terminus through at least one of the group consisting of:the bulb; the web; and the horizontal planar support; wherein thereinforcing members are prestressed and the beam is cast from concreteas a unitary body.
 2. The beam of claim 1, further comprising an endblock formed at the first terminus and the second terminus, each endblock formed as a vertical extension of the vertical opposed side edgesbetween the bulb to the flanges; wherein the end block is cast fromconcrete as part of the unitary body.
 3. The beam of claim 1, whereinsaid plurality of diaphragms are formed as pairs between respectivesides of the web and respective flanges at the same longitudinalposition along the beam.
 4. The beam of claim 3, wherein said pairs ofdiaphragms are spaced apart by a spacing distance, and wherein thespacing distance sufficient such that a load applied to an outer portionof one of the flanges will be transmitted to the web via one of thediaphragms.
 5. The beam of claim 4, wherein the spacing distance is lessthan 30 times a flange thickness of the flanges.
 6. The beam of claim 1,further comprising laterally extending internal reinforcements at leastat longitudinal positions coinciding with the diaphragms.
 7. The beam ofclaim 3, further comprising laterally extending internal reinforcementsat least at longitudinal positions coinciding with the diaphragms. 8.The beam of claim 2, wherein said plurality of diaphragms are formed aspairs between respective sides of the web and respective flanges at thesame longitudinal position along the beam.
 9. The beam of claim 8,wherein said pairs of diaphragms are spaced apart by a spacing distance,and wherein the spacing distance sufficient such that a load applied toan outer portion of one of the flanges will be transmitted to the webvia one of the diaphragms.
 10. The beam of claim 9, wherein the spacingdistance is less than 30 times a flange thickness of the flanges. 11.The beam of claim 8, further comprising laterally extending internalreinforcements at least at longitudinal positions coinciding with thediaphragms.
 12. A long span vehicle bridge structure including aplurality of beams according to claim
 1. 13. A long span vehicle bridgestructure including a plurality of beams according to claim
 2. 14. Along span vehicle bridge structure including a plurality of beamsaccording to claim
 3. 15. A long span vehicle bridge structure includinga plurality of beams according to claim
 4. 16. A long span vehiclebridge structure including a plurality of beams according to claim 5.17. A long span vehicle bridge structure including a plurality of beamsaccording to claim
 6. 18. A long span vehicle bridge structure includinga plurality of beams according to claim 7.